diff --git a/packages/endomoat/test/scenario-util.js b/packages/endomoat/test/scenario-util.js
index 15d28b78ce..451f812bdb 100644
--- a/packages/endomoat/test/scenario-util.js
+++ b/packages/endomoat/test/scenario-util.js
@@ -219,7 +219,8 @@ export function createScenarioRunner(log = console.error.bind(console)) {
       outputPromise?.catch(() => {})
     }
 
-    if (stderr) {
+    // nothing should output to stderr. except a debugger
+    if (stderr && stderr.trim() !== 'Debugger attached.') {
       throw new Error(`Unexpected output in standard err: \n${stderr}`)
     }
     try {